package com.sinosoft.utils;
import java.io.ByteArrayOutputStream;
public class Base64Util{
	private static final char [] legalChars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/" .toCharArray();    

	private static char[] base64EncodeChars = new char[] {    
		 'A', 'B', 'C', 'D', 'E', 'F', 'G', 'H',
		 'I', 'J', 'K', 'L', 'M', 'N', 'O', 'P',
		 'Q', 'R', 'S', 'T', 'U', 'V', 'W', 'X',
		 'Y', 'Z', 'a', 'b', 'c', 'd', 'e', 'f',
		 'g', 'h', 'i', 'j', 'k', 'l', 'm', 'n',
		 'o', 'p', 'q', 'r', 's', 't', 'u', 'v',
		 'w', 'x', 'y', 'z', '0', '1', '2', '3',
		 '4', '5', '6', '7', '8', '9', '+', '/',};    
	   
	   private static byte[] base64DecodeChars = new byte[] {    
	   -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,    
	   -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1,    
	   -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 62, -1, -1, -1, 63,    
	   52, 53, 54, 55, 56, 57, 58, 59, 60, 61, -1, -1, -1, -1, -1, -1,    
	   -1,  0,  1,  2,  3,  4,  5,  6,  7,  8,  9, 10, 11, 12, 13, 14,    
	   15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, -1, -1, -1, -1, -1,    
	   -1, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40,    
	   41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, -1, -1, -1, -1, -1 };    
 
	   public static byte[] decode(String str) {    
	       byte[] data = str.getBytes();    
	       int len = data.length;    
	       ByteArrayOutputStream buf = new ByteArrayOutputStream(len);
	       int i = 0;    
	       int b1, b2, b3, b4;    
	    
	       while (i < len) {     
	           do {    
	               b1 = base64DecodeChars[data[i++]];    
	           } while (i < len && b1 == -1);    
	           if (b1 == -1) {    
	               break;    
	           }    
	              
	           do {    
	               b2 = base64DecodeChars[data[i++]];    
	           } while (i < len && b2 == -1);    
	           if (b2 == -1) {    
	               break;    
	           }    
	           buf.write((int) ((b1 << 2) | ((b2 & 0x30) >>> 4)));    
	               
	           do {    
	               b3 = data[i++];    
	               if (b3 == 61) {    
	                   return buf.toByteArray();    
	               }    
	               b3 = base64DecodeChars[b3];    
	           } while (i < len && b3 == -1);    
	           if (b3 == -1) {    
	               break;    
	           }    
	           buf.write((int) (((b2 & 0x0f) << 4) | ((b3 & 0x3c) >>> 2)));    
	               
	           do {    
	               b4 = data[i++];    
	               if (b4 == 61) {    
	                   return buf.toByteArray();    
	               }    
	               b4 = base64DecodeChars[b4];    
	           } while (i < len && b4 == -1);    
	           if (b4 == -1) {    
	               break;    
	           }    
	           buf.write((int) (((b3 & 0x03) << 6) | b4));    
	       }    
	       return buf.toByteArray();    
	   }

	   public static String encode( byte [] data) {    
	        int start = 0 ;    
	        int len = data.length;    
	        StringBuffer buf = new StringBuffer(data.length * 3 / 2 );    
	         
	        int end = len - 3 ;    
	        int i = start;    
	        int n = 0 ;    
	         
	        while (i <= end) {    
	            int d = (((( int ) data[i]) & 0x0ff ) << 16 ) | (((( int ) data[i + 1 ]) & 0x0ff ) << 8 ) | ((( int ) data[i + 2 ]) & 0x0ff );    
	         
	            buf.append(legalChars[(d >> 18 ) & 63 ]);    
	            buf.append(legalChars[(d >> 12 ) & 63 ]);    
	            buf.append(legalChars[(d >> 6 ) & 63 ]);    
	            buf.append(legalChars[d & 63 ]);    
	         
	            i += 3 ;    
	         
	            if (n++ >= 14 ) {    
	                n = 0 ;    
	                buf.append( " " );    
	            }    
	        }    
	         
	        if (i == start + len - 2 ) {    
	            int d = (((( int ) data[i]) & 0x0ff ) << 16 ) | (((( int ) data[i + 1 ]) & 255 ) << 8 );    
	         
	            buf.append(legalChars[(d >> 18 ) & 63 ]);    
	            buf.append(legalChars[(d >> 12 ) & 63 ]);    
	            buf.append(legalChars[(d >> 6 ) & 63 ]);    
	            buf.append( "=" );    
	        } else if (i == start + len - 1 ) {    
	            int d = ((( int ) data[i]) & 0x0ff ) << 16 ;    
	         
	            buf.append(legalChars[(d >> 18 ) & 63 ]);    
	            buf.append(legalChars[(d >> 12 ) & 63 ]);    
	            buf.append( "==" );    
	        }    
	         
	        return buf.toString();    
	    }
}
